Integrated circuit laser devices are manufactured on wafers which are two inches in diameter and about 12-20 mils thick. After initial manufacture, the wafers are thinned to about 3.5-4.5 mils and separated into smaller units, called sections, with four sections being derived from a single wafer. The sections are trimmed in one dimension, which we will call length, to be about 0.4 inches long. They are also scored across their widths to form 20-30 subdivisions, called bars, which are about 12 mils wide and about 0.4 inches long.
During subsequent processing, the sections are divided into bars by breaking or cleaving them along the scribe lines, to form facets along their elongated sides. After the cleaving process, the cleaved laser bars are transported side-by-side on a plastic film sheet, with their lengths extending laterally of the sheet.
Testing of the individual laser devices on each bar is often performed at this time. However this currently requires that the bars be removed from the film sheet and be subjected to a considerable amount of physical handling, in order to be placed into and subsequently removed from a testing fixture. There is a substantial risk that the bar or some of the devices on it will be damaged or destroyed in the course of such handling.
In accordance with the present invention, the film carrying the laser bars is passed over an elongated pedestal which is aligned with the film sheet.
The pedestal has a width which is less than the length of a laser bar, so that the unsupported portion of the plastic film under the ends of the laser bars may be drawn downward and away from the bar. This provides access to the metalized underside of the bar, which serves as a common N-contact for all of the laser chips on the bar. A probe is placed in contact with the undersurface of the bar, and at least one additional probe is placed in contact with a P-contact on one of the laser devices. A chip activation signal is applied between the two probes, and a sensor detects whether or not the chip being probed emits radiation. Failure to emit radiation or to emit radiation in an expected manner is indicative of a bad chip.